1. Field of the Invention
This invention relates generally to devices used to clear obstructions in body passageways, more particularly, this invention relates to apparatuses and methods of treating such obstructions by the infusion of chemical thrombolytic agents. Yet more particularly, this invention relates to catheters and to catheter systems for exposing vascular obstructions to therapeutic agents, generally to effectuate their removal.
2. Description of the Prior Art
The use of catheter systems to treat various medical conditions has been known for some time. In treating a particular area within a body passageway, it is often desirable to isolate the area to be treated from the rest of the body. One approach to isolating a treatment area is the placement of one or more inflatable balloons proximal or distal (or both) to the treatment area. Inflating the balloon or balloons serves to isolate the vascular structure to be treated and permits control of the length of time of exposure. U.S. Pat. No. 2,936,760 issued to Gants, U.S. Pat. No. 4,022,216 issued to Stevens, and U.S. Pat. No. 4,705,502 issued to Patel describe catheters designed for use in the urinary tract.
Catheter systems are also used in other applications. U.S. Pat. No. 4,696,668 issued to Wilcox, for example, describes a catheter system for treatment of nasobiliary occlusions. Similarly, U.S. Pat. No. 4,198,981 issued to Sinnreich is used in intrauterine applications. U.S. Pat. No. 4,453,545 issued to Inoue discloses an endotracheal tube.
One of the most common applications for catheter systems is the treatment of occlusions within the cardiovascular system. A catheter system for venous applications is seen in U.S. Pat. No. 4,795,427 issued to Helzel. U.S. Pat. No. 4,636,195 issued to Wollinsky, U.S. Pat. No. 4,705,507 issued to Boyles, and U.S. Pat. No. 4,573,966 issued to Welkl et al., all describe catheter systems designed to infuse a liquid for the treatment of an arterial occlusion. Each of these devices has one or more balloons which can be inflated to occlude the artery during the treatment process.
U.S. Pat. No. 4,655,746 issued to Daniels et al. discloses the use of two concentric catheters defining an interlumenal space therebetween. Each of the catheters has its own balloon to isolate (adjustably) a portion of the body passageway. The Daniels et al. design, however,. requires the use of the interlumenal space as a fluid passageway, thereby complicating the construction and operation of the device.
U.S. Pat. No. 4,927,418 to Dake et al. discloses a catheter for uniform distribution of therapeutic fluids. The Dake et al. catheter utilizes a relatively thick-walled tubular body having a plurality of smaller lumens therein in conjunction with a larger central lumen discharging fluid from the catheter.
U.S. Pat. No. 5,059,178 to Ya uses balloons to subtend a blood vessel upstream and downstream of a thrombus. Thrombus dissolving agent is supplied to the zone between the balloons. An expansion catheter having a third balloon is used to expand a location of structure remaining after removal of the dissolved thrombus.
The present invention provides an apparatus, a method, and a kit for treating an obstruction in a body passageway, such as a vein or an artery, through the infusion of a fluid. In one aspect the present invention is a catheter for administering therapeutic agent to an obstruction within a vascular system. A catheter of this invention has a fixed length infusion zone generally defined by one or more inflatable balloons and a series of infusion orifices located therebetween. A catheter of this invention comprises a cylindrical catheter body. The cylindrical catheter body comprises a wall, the wall having distal and proximal ends. One of the distal or proximal segment ends of the catheter wall body has a balloon means located thereon. The wall further includes or defines a plurality of radial orifices.
The catheter body also interiorly defines a primary lumen, the primary lumen extending through the catheter body to couple, fluidically, the orifices and its distal and proximal ends. The primary lumen has a larger diameter segment beginning adjacent the proximal end of the catheter and extending the majority of the length of said catheter body, and a smaller diameter segment located interiorly adjacent the distal end of the catheter body and distal to the orifices. The reduced diameter segment of the primary lumen is adapted to cooperate with a separate occluder means (described below) to restrict fluid flow out the distal end of the first lumen and to force such fluid to flow radially from the orifices.
The diameter of the primary lumen, with the exception of the extreme distal portion, is in the range of about 0.16 inches to about 0.065 inches while the diameter of the smaller diameter segment is in the range of about 0.014 inches to about 0.060 inches.
The catheter body of a catheter of this invention, preferably, also defines at least a second lumen, the second lumen being in fluid communication with the balloon means and the proximal end of the catheter body so as to permit said balloon means to be inflated therefrom.
The diameter of said plurality of second lumens is in the range of about 0.009 inches to about 0.025 inches.
In a preferred practice of this invention, two balloons are used to isolate the treatment area from the remainder of the body so that therapeutic agent may be infused therearound. One of each of the balloons is located on the catheter wall upstream and downstream of the infusion ports.
In another aspect, the present invention is a method of treating an obstruction, such as thrombus, within a vascular structure. (The location of the obstruction has been previously identified by methods well known to this art.) A method according to this invention comprises the steps of first advancing a steerable guidewire through the vasculature until the distal tip thereof is adjacent i.e., in the vicinity or proximate to, the previously located obstruction or diseased segment to be treated. Next, a catheter having a structure as described above is advanced or slid over the guidewire until the infusion zone is located at the treatment site. At this juncture, the spatial relationship between the obstruction and the catheter/guidewire structure will determine the next step. If the steerable guidewire/catheter combination/structure cannot be positioned through the obstructed segment, then the guidewire is removed from the catheter and an occlusion means, occlusion wire, or tip occluder wire, is advanced through the primary lumen thereof. If the catheter/guidewire combination structure can be passed through the vascular obstruction, utilization of the steerable catheter guidewire/conbination continues. While utilization of the steerable wire is preferred, a non-steerable tip occluder wire permits the extreme distal portion of the catheter to be positioned more closely to, for example, thrombus which cannot be crossed with a steerable wire. Withdrawing a steerable guidewire into the catheter body, which would permit the catheter to be positioned more closely to the treatment site, tends to restrict radial fluid delivery due to restriction of diameter of the primary lumen. Both the steerable guidewire and the occlusion means or tip occluder wire have an enlargement adjacent their distal ends which cooperate with the reduced diameter portion of the primary lumen substantially to prevent fluid from passing distally from the catheter.
Whether the tip occluder or steerable guidewire is used, the next step is to inflate the balloon means to define the treatment area. Lastly, thrombolytic agent is introduced into the primary lumen and subsequently exits or infuses from the radial passages to the infusion zone to treat the obstruction.
In a preferred practice of this method, the catheter includes a plurality of balloons located distally and proximally with respect to the orifices. The balloons are fluidically coupled to the proximal end of the catheter by means of secondary lumens which permit the balloons thereby to be inflated and deflated. Thrombolytic agents may include urokinase, streptokinase, tissue plasminogen activator (TPA), or a similar therapeutic species. As the lesion within the treatment area is exposed to the thrombolytic agent, some of the material is dissolved and is removed therefrom.
In a preferred practice of the above method, a radiopaque structure on the catheter, usually on its distal segment, is monitored while the catheter is positioned within the vasculature. A plurality of radiopaque structures, such as platinum rings or bands, may be disposed along the length of the catheter, and on the steerable guidewire and on the occluder wire. These structures appear more intense than adjacent, non-radiopaque materials under fluoroscopic examination. Generally, a steerable guidewire will have a radiopaque distal tip and possibly additional proximally-located radiopaque structures. By observation of these radiopaque structures, the progress of the catheter into the vasculature can be observed, the location of the balloon or balloons (and therefore the infusion zone) relative to the treatment site can be determined, and the relationship between the catheter and the guidewire or occluder wire can be monitored. Utilization of the cooperatively located radiopaque structures in catheter placement and in therapeutic application is a particularly advantageous aspect of the present methods.
Yet a further aspect of this invention comprises a kit. A kit of this invention comprises an occluder means such as a tip occluder wire having an enlargement adjacent its distal end and a steerable guidewire. The guidewire preferably has an enlargement adjacent its distal end, thereby incorporating the features of both a steerable guidewire and a non-steerable occluder wire. The diameter of the enlargement of either or both of the guidewire or occluder wire is determined by the interior diameter of the reduced diameter segment of the primary lumen of the catheter. A kit having at least the above three components offers medical personnel employing a catheter of this invention the ability to maximize their options with respect to patient treatment. Kit components may include other necessary or desirable equipment such as stopcocks, syringes and gloves.